Method and means for the production of porous clinkers



. A. F. BOMGREN vMETHOD AND MEANS FOR THE PRODUCTION OF POROUS CLINKERS Filed Feb. 20, 1948 Feb. 21, 1950 Patented Feb. 21, 1950 OFFICE METHOD AND MEANS FOR THE PRODUC- TION F POROUS CLINKERS Axel Fritiof Bomgren, Stockholm, Sweden Application February 20, 1948, Serial No. 9,875 In Sweden July 5, 1946 Section 1, Public Law 690, August Patent expires July 5, 1966 7 Claims. 1

The present invention refers to a method and an apparatus for the production of porous clinkers adapted to be used for the manufacture of light-concrete therefrom. To provide for a high heat-insulating capacity, such clinkers should have a volumetric weight as low as possible. Furthermore, they should possess a strength as great as possible, since the strength of the lightconcrete is primarily dependent on the strength of the clinkers employed.

The invention is substantially distinguished by the feature that dried and granulated slate-clay, or other shale or clay capable of developing gas when heated, is first heated slowly to a relatively low temperature (about 800 C.) in a furnace, wherein the granular material is stored within a comparatively high space, water contained in the mass being thus caused to escape, whereupon the mass is spread in a thin layer, and is rapidly heated to a higher temperature (approximately 1200-l300 C.) a glaze layer being thus formed on the surface of the grains, the volume of which is augmented at the formation of gas.

It is important, in order to attain the desired result, that the heating be effected in twostages. In the first stage, the grains are heated slowly to a temperature of 800-900 C., any water contained in the starting material being thus caused to escape. In the second stage, the grains are subjected to a rapid heating to a temperature approximately between 1200 and 1300 C., the above-mentioned development of gas being thus initiated, so that the interior of the grains becomes porous. At the same time a glaze layer is formed on the surface of the grains. In this second rapid heating procedure, a certain risk of the grains getting caked is incurred, which need not be feared in the previous preheating, since such caking occurs only at temperatures exceeding 1000" C. To avoid this drawback, the grains should, according to the invention, lie free from one another as far as possible during the second heating stage, which is preferably attained by the spreading of the grains in a single layer. It is not necessary to restrict the time of the second heating procedure; it has been found, however, that this heating stage need not be extended over any long time. On the other hand, the first heating to 800-900" C. must take place slowly, as stated above, for which reason it takes a comparatively long time. In order that this preheating shall permit of being accomplished in a rational way and with the best economy, it is preferably carried into effect in a. large vertical furnace, wherein a great quantity of the material may thus be stored within a high space, without the risk of caking being incurred. During the following rapid heating, in which the grains are to lie practically in a single layer, it will be found suitable to make use of an annular tunnel furnace with a. rotating bottom slab. The furnace should be dimensioned so as to permit of taking up some of the material preheated in the contrivance for the pretreatment, such as the vertical furnace. It has been found that no risk of caking manifests itself before a temperature of about 1000" C. is reached.

The exhaust gases from the tunnel furnace, which have a temperature of approximately 800 C., may preferably be used for the heating of the furnace of pre-treatment. The exhaust gases from the latter furnace should preferably have a temperature of only about 200 C. The supply of gas to the tunnel furnace should preferably be effected in such a manner that the material, when entering the furnace, will first be brought into contact with gases of a temperature of about 800 C., whereupon the material when passing through the furnace is brought into contact with hotter and hotter gases, so as to reach the highest temperature immediately before being discharged from the furnace. The heating of the furnace may preferably be effected by means of oil burners.

The accompanying drawing illustrates a form of embodiment of an apparatus according to the invention. Fig. l is a vertical view of the heating contrivance, Fig. 2 is a plan View, and Fig. 3 a section through the same on line IIIIII in Fig. 2.

l designates a vertical furnace, in which the granular material is preheated. The height of the layer of the material is considerable in this furnace, and may amount to a few decimeters.

The vertical furnace is heated by the exhaust gases from the annular tunnel furnace adapted for the heating to a higher temperature. This should preferably take place in such manner that the warm exhaust gases holding a temperature of about 800 C. enter the vertical furnace from below. When ascending in the vertical furnace, the gases are cooled down furthermore, so that they will escape from the furnace at a temperature of approximately 200 C. The heat is then transferred from the gases to the material progressing downwardly through the vertical furnace, which material shows a temperature of about 800 C. at the bottom of the furnace. The

passage of the material through the vertical fur-' nace takes approximately 1 to 2 hours.

The vertical furnace has a conical bottom 2,

through which the preheated material passes to an outlet channel 3, which is provided with a cut-off damper 4. The lower portion of the outlet channel opens into the tunnel furnace 6, in a manner such that the material discharged from the outlet channel falls down on the rotating bottom slab 5 of the tunnel furnace. Means not shown in the drawing may be provided in the from the -,channei.3, on the rotating bottem slab 5 of the .tunnel furnace. a The rate at which the pretreated material is discharged from the channel 3, and the rate at: which the bottom $1811) of the tunnel ,furnace 6; rotates, must be so adapted that the grains ion the bottom slab form a uniform single. layer, wherein the grains lie free from one another. While the bottom slab 5 of the tunnel furnace 6 is arranged to rotate, the vault proper "l of the same is stationary. Oil burners -8'-1are provided iprising a vertical kiln providing a straight path for-,adescending mass of the dried and granulated material and a rising flow of hot gases, a single annu lar' tunnel furnace connected to the said kilnv and having a rotating plane bottom slab,

.for the heating of the tunnel furnace, preferably I in such manner that the material, on having ;.e n-

tered the tunnel furnace, is first brought into contact with the exhaustgases having the lowest temperature, that is to say about 800 '.C., and is 'thenjlorought into contact with hotter, hotter.

:efiS'esQso as to reach by degrees a temperature between 1200and1300" C. The size Of the tun-.

nel furnace and the rotational speed of the bottomslab must .be adapted sothat the clay grains on having once passed through the tunnel ,fur nace are transformed into the .desired final produc't,"th at is to say form a poro-us clinker having.

a surface coated by a glaze layer.

" The discharge of the finished material irorn the tunnel.iurnaceiseffected bymeans of a worm? conveyor ,9 and .a plough-like scraper connected thereto, saidscraperkbea-ring on the bottom slab,

while .not being shown in the drawing. .If desired, the conveyor and the-scraper may be pro- Vided with cooling meananot shown in the-drawins, which protect them against damage through the influence ofth hot clinker ,material.

WhatIclaim is:

and shale type and capable of developing {gas when heated which comprises the steps :of storing the material in a comparatively thick vertical column, slo,w.ly heating in a ,heating stage .the materialso stored to atemperature of about -'80.0 C. to cause any water contained in the material to escape,tspreading the-material in a layer in which the individual granules .lie ,substantially free from one .another, and rapidly heating the material .in :a second-sta e to -,a temperature within a range a-between v12l0 0 and 1.30m

comparatively great -;amount of the .material is.

which 3F 1.. The .methodrof producing porous clinkers from dried and granulated material of theelay .stored in avertical column in-which the granules :arein contact .with. each other both-vertically and horizontally, and in which the second heating.

.stage is carried out while .a. minor amountof the :material isspread in a substantially singlehori- :zontal layer inwhich there isnot more than point .contactin substantially one horizontal plane ,be-

amount of' the material storedin a vertical column is. heated by meansof the exhaust gasesprevi rously used .forheatingsaidminor amount, thesaid exhaust; gases beingi caused to flow in -upward direction through the-material stored in a ve tical column. e

Apparatus, for producing from .dried andzgranulatedmaterial of ;the,.clay

andyshale n 1 and tenable .cf .adevelopingrgas porous clinkers- 'means forheating the tunnel furnace to a temperature exceeding that of the kiln means for ..:-the control of the passage of the material preheated in the kiln from the kiln to the rotating bottom slab in such a manner that the granules on the bottom slab form a layer wherein the granules substantially lie tree-from one. another, aridrnean for discharging the material from the; bottom slab after, the same has once passed. through the annular tunnel furnace. v Apparatus according to claim 4 in which the. connection between the tunnel furnace and the. kiln is arranged in such a way as to permi the: entrance of the exhaust gases escaping from, the tunnel turnaee into the bottom of the kiln. 6. Apparatus according to claim 4: in which. the discharging means consist of a plough-like scraper and a worm conveyor providedwith cooling means. 1 7. Apparatus for producing porous clinkers from dried and granulated material of-the clay and Sha e ype and capable of developing gas Whenheated in which clinkers the volume of the gran u-ar material is augmented and which have a glaze layer on the surface, said. apparatus comprising ,a vertical kiln providing a straight. path. for a descending mass of the dried and granulated material and a rising flowof hot gasesa single annular tunnel furnace connected tosaid. kilnv and having a rotating plane bottom slab, means for thecontrol ,of the passage of the mate? rial heated inthe kiln from the kiln to the rotat-- ingbottom slab in such a manner that the granules on the bottom slab form a substantially single. layer wherein .at least the majority of the gran: ules lie free from one another, means for heat-j ing the tunnel gfurnace and the kiln comprising oil lourners arranged in the tunnel furnace in such ,a manner that the material when entering thegf-ur-nace is in contact with ases already rela-. tively cooled and in contact. with the hottest gases when havingv reached a. position in the tunnel furnace adjacent to the point of discharge, the connection between the tunnel furnace and the? being such as to permit the entrance of the exhaust gases escaping from the tunnel furnace},

, into the bottom of the kiln, and means for. .dis-' charging the material from the bottom slab after the same has once passed throughthe .annular tunnel furnace. 

1. THE METHOD OF PRODUCING POROUS CLINKERS FROM DRIED AND GRANULATED MATERIAL OF THE CLAY AND SHALE TYPE AND CAPABLE OF DEVELOPING GAS WHEN HEATED WHICH COMPRISES THE STEPS OF STORING THE MATERIAL IN A COMPARATIVELY THICK VERTICAL COLUMN, SLOWLY HEATING IN A FIRST HEATING STAGE THE MATERIAL SO STORED TO A TEMPERATURE OF ABOUT 800*C. TO CAUSE ANY WATER CONTAINED IN THE MATERIAL TO ESCAPE, SPREADING THE MATERIAL IN A LAYER IN WHICH THE INDIVIDUAL GRANULES LIE SUBSTANTIALLY FREE FROM ONE ANOTHER, AND RAPIDLY HEATING THE MATERIAL IN A SECOND STAGE TO A TEMPERATURE WITHIN A RANGE BETWEEN 1200* AND 1300* C. WHILE MAINTAINING THE GRANULES IN SAID LAYER IN A MUTUALLY UNMOVED POSITION.
 4. APPARATUS FOR PRODUCING POROUS CLINKERS FROM DRIED AND GRANULATED MATERIAL OF THE CLAY AND SHALE TYPE AND CAPABLE OF DEVELOPING GAS WHEN HEATED IN WHICH CLINKERS THE VOLUME OF THE GRANULAR MATERIAL IS AUGMENTED AND WHICH HAVE A GLAZE LAYER ON THE SURFACE, SAID APPARATUS COMPRISING A VERTICAL KLIN PROVIDING A STRAIGHT PATH FOR A DESCENDING MASS OF THE DRIED AND GRANULATED MATERIAL AND A RISING FLOW OF HOT GASES, A SINGLE ANNULAR TUNNEL FURNACE CONNECTED TO THE SAID KILN AND HAVING A ROTATING PLANE BOTTOM SLAB, MEANS FOR HEATING THE TUNNEL FURNACE TO A TEMPERATURE EXCEEDING THAT OF THE KIN MEANS FOR THE CONTROL OF THE PASSAGE OF THE MATERIAL PREHEATED IN THE KILN FROM THE KILN TO THE ROTATING BOTTOM SLAB IN SUCH A MANNER THAT THE GRANULES ON THE BOTTOM SLAB FORM A LAYER WHEREIN THE GRANULES SUBSTANTIALLY LIE FREE FROM ONE ANOTHER, AND MEANS FOR DISCHARGING THE MATERIAL FROM THE BOTTOM SLAB AFTER THE SAME HAS ONCE PASSED THROUGH THE ANNULAR TUNNEL FURNACE. 